bhg //Another interesting question - what will Camilla become if she outlives King Charles? She can't be Queen Mother because she's not the mother of King William. //
////Assuming Camilla outlives Charles, she will be given a different title after his death. At that point Prince William will become the king and Camilla will have a new role as the former Princess Consort or Queen Consort.
Traditionally, the widowed spouse of the former king is called the “dowager queen.” Queen Elizabeth’s mother, whose name was also Elizabeth, called herself “The Queen Mother” to distinguish herself from her daughter. But technically she was a dowager queen after King George VI died.////
https://www.cheatsheet.com/entertainment/camilla-parker-bowles-new-title-when-prince-charles-dies.html/